Benjamin graduated from the Cave Hill Campus of the University of the West Indies in 1975 with the LL.B. degree and in 1977 he obtained the Certificate of Legal Education from the Hugh Wooding Law School in Trinidad and Tobago. While practicing as a solicitor and attorney-at-law in Guyana he served as an acting stipendiary magistrate and as assistant judge advocate for the Guyana Defence Force.
In 1988, Benjamin was appointed as a magistrate in Antigua and Barbuda and became the chief magistrate in 1991. He ascended the High Court bench of the Eastern Caribbean Supreme Court in 1993 and has since sat in Antigua-Barbuda, Montserrat, British Virgin Islands, Grenada and St Lucia.
He last held the position of presiding judge of the Criminal Division of the High Court in St Lucia, a pioneering position that is aimed at streamlining the criminal trial process utilizing case management techniques.
Benjamin is a Fellow of the Commonwealth Judicial Education Institute and a member of the Commonwealth Magistrates and Judges Association.